1. Field of the Invention
This invention relates to a stroller, and more particularly to a wheel assembly for a stroller, which includes a single wheel.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional stroller 1 is shown to include a stroller frame 10 with four legs 101, two front wheel assemblies 11 mounted respectively to two of the legs 101, and two rear wheel assemblies 12 mounted respectively to the other two of the legs 101. FIG. 2 is a bottom view of one of the front wheel assemblies 11. Each of the front wheel assemblies 11 includes two front wheels 13, a wheel seat 14 disposed between the front wheels 12, and a wheel axle 15 extending through the front wheels 13 and the wheel seat 14. Each of the wheel seats 14 has a leg-connecting portion 141 sleeved rotatably on a respective one of the legs 101, and an axle-connecting portion 142, within which the wheel axle 15 is journalled. To enhance the comfort of the baby carried on the stroller 1, a vibration-absorbing device (not shown) can be disposed within the axle-connecting portion 142 of each of the wheel seats 14.
When it is desired to push the stroller 1 to advance along a straight path, a forward force (A) is applied to the stroller frame 10. In each of the front wheel assemblies 11, since the forward force (A) is located midway between two frictional forces (B) that are generated between the ground and the front wheels 13 and since the direction of the forward force (A) is parallel to those of the frictional forces (B), the stroller 1 can advance along a straight path 16. When the stroller 1 moves over a lawn or uneven road surfaces, it is necessary for the stroller wheels to have a large diameter so as to ensure the comfort of the baby. However, if each of the front wheel assemblies 11 has two large-diameter front wheels 13, the total volume and weight of the stroller 1 will increase significantly so that it is difficult to push the stroller 1.